It is known in the art of casting to provide a supporting element, a "box stud", having upper and lower support plates connected by a bar-like separation element for being placed between form surfaces. Published German Patent Application No. 2,258,831 shows such a supporting element.
A prior-art supporting element is attached to the core surface by using nails which pass through perforations in upper or lower supporting plates. These nails are driven into the molding sand of the core and thus require a significant amount of labor. Furthermore, in practice it has been found that automatic nailing machines are not useful in this operation and that the nailing frequently damages the molding sand.
It is also known, for example, from published German Patent Application No. 2,923,702 that the supporting element can be glued to the front surface of a core. This type of supporting element suffers from the disadvantage that it cannot be placed on the core surface by an automatic setting machine because the elements become glued together in the feeder box of the automatic setting machine. Furthermore, coating with glue requires an additional step which adds expense to the operation.
It is also known to provide support plates with front faces having a plurality of concentric ribs of semi-circular cross section. The ribs are designed to extend into the molding sand to thereby increase the resistance to moving the supporting elements with respect to the core surface. This has not been successful, however, for several reasons. The supporting elements are small, light objects that do not effectively penetrate into the molding sand which has typically been soaked with furan resin. The distance between the outer extent of the ribs and the form surface is so small that liquid metal cannot flow between a support plate and the surface of the mole sand, thus producing an unsightly depression in the surface of the finished casting. The provision of the ribs also results in additional cost.